When Paul Greengrass directs a thoroughly dramatic tale based on true events and Tom Hanks takes on the title role, you think you know what to expect. But just you wait — the piercingly realistic "Captain Phillips" will exceed your expectations.

The story of the six days that Richard Phillips, captain of the cargo ship Maersk Alabama, spent in April 2009 first trying to avoid a gang of Somali pirates and then as their restive captive, this film does an impeccable job of creating and tightening the narrative screws. The result is so propulsive that you may find yourself looking at your watch not out of boredom but because you're not sure how much more tension you can stand.

But "Captain Phillips," based on the real man's memoir, is more than a reaffirmation of how good Greengrass, responsible for both "The Bourne Supremacy" and "The Bourne Ultimatum," is at the delicious mechanics of crackerjack storytelling.

As written by Billy Ray, who wrote and directed "Shattered Glass," this film has qualities we might not expect. This is a film with an emotional quotient that manages to combine the dynamics of human behavior under stress with our affinity for the nuts and bolts of realistic action.

More than that, harking back to "Bloody Sunday," Greengrass' first international success and the film that revealed his gift for based-on-fact dramas, "Captain Phillips" has also managed to include some subtle but unmistakable social commentary that speaks, the director has said, "to the larger forces shaping our world today." Tense drama, top acting, topical relevance and thoroughgoing realism, this is a film that reminds us what we've been missing, and does it all without breaking a sweat.

That kind of involvement was a special challenge with a story whose every detail was covered to death by the major media. Greengrass made it happen with a canny mix of known, unknown and completely inexperienced actors, all of whom had to be broken into the director's very particular filmmaking style.

Few actors are better known than two-time Oscar winner Hanks, who, after an unfortunate "Cloud Atlas" detour, is back in his wheelhouse here as the above-average average man who possesses the kind of everyday heroism it's easy to both identify with and believe in. As good as Hanks has been in the past, there are moments here, especially near the conclusion, that are deeper and more emotional than anything we've seen from this actor before.

Except for a brief cameo by Catherine Keener as the captain's wife, Andrea, no one else in the almost exclusively male cast will be known to most moviegoers, but this works to the film's advantage by increasing believability across the board.

This is especially the case with the quartet of Somali Americans — all without acting experience and all discovered in the Minneapolis area by casting director Francine Maisler and her Minnesota colleague Debbie DeLisi — who play the pirates who bedevil the Maersk Alabama. They are a sepulchral bunch, thinner than thin every one and, especially the leader Muse (Barkhad Abdi) and his enforcer Najee (Faysal Ahmed), initially looking scary enough to be capable of anything.

Greengrass, who had extensive documentary experience before turning to features, likes to shoot in long, unbroken sequences using two or three hand-held cameras, a style he feels enhances the believability he is passionate about.

For that reason, Hanks and the Somalis did not meet each other until the moment the pirates, looking like men from another planet, storm the Maersk Alabama's bridge. "The verisimilitude was just incalculable," Hanks comments in the press notes. "The hair stood up on the back of our necks."

Before that "when worlds collide" moment, both sides have been carefully introduced to us, Phillips in some regular guy moments at his Vermont residence and the pirates, in sequences not in the book, in their home in the seaside town of Eyl, Somalia.

It's there that we get the crucial sense of why these men — impoverished former fishermen without prospects and under the thumbs of armed and dangerous warlords — do what they do. "Captain Phillips" in no way condones piratical behavior, but it does want us to see the men as feeling trapped into roles they would not have otherwise chosen.

As much a personality as any of the men is the Maersk Alabama, an enormous 508-foot vessel capable of holding close to 1,100 railroad car-sized containers. Greengrass, a bear for authenticity, moved the production to Malta to be able to shoot on the Maersk Alexander, the Alabama's sister ship, just as he moved everything to Norfolk, Va., to get access to the appropriate U.S. Navy vessels.